Technical Abstract:
Ricin is a potent protein toxin present in the seeds of Ricinus communis (castor) plants. The intentional adulteration of food with ricin as an instrument of bioterrorism is a matter of increasing concern. We hypothesized that a real-time PCR assay could be used to detect the castor nucleic acid that remains associated with crude toxin preparations, such as those that might be used in a bioweapon. In this study, we developed a SYBR Green I Dye-based real-time PCR method for the quantitative detection of ricin and its homologues in food. A pair of castor-specific primer was identified for sensitive detection of castor contamination in food samples. Of three different DNA extraction protocols compared, CTAB method was selected for spiked ground beef to determine detection limits of castor DNA fragments by real-time PCR. Castor-specific DNA amplification was obtained when spiking as little as 0.001% of castor acetone powder in ground beef samples, indicating excellent sensitivity for the assay. This sensitivity is compared to the results of ELISA.